Copper doped methylene blue sensitized poly(vinyl alcohol) (MBPVA)–acrylamide films were fabricated to improve the
storage life of recorded gratings. The films were fabricated using gravity settling method and the copper chloride
concentration was optimized as 3:18 10 3 mol/l for a dye concentration of 6:2 10 4 mol/l. The gratings recorded on the
optimized film constitution could be stored for months with stable diffraction efficiency (24%) without any chemical or
thermal fixing techniques. The resolution of the material is found to be unaffected with the addition of copper chloride.

Thin film solar cells having structure CuInS2/In2S3 were fabricated using chemical spray pyrolysis (CSP) technique
over ITO coated glass. Top electrode was silver film (area 0.05 cm2). Cu/In ratio and S/Cu in the precursor solution
for CuInS2 were fixed as 1.2 and 5 respectively. In/S ratio in the precursor solution for In2S3 was fixed as 1.2/8. An
efficiency of 0.6% (fill factor -37.6%) was obtained. Cu diffusion to the In2S3 layer, which deteriorates junction
properties, is inevitable in CuInS2/In2S3 cell. So to decrease this effect and to ensure a Cu-free In2S3 layer at the top of
the cell, Cu/In ratio was reduced to 1. Then a remarkable increase in short circuit current density was occurred from 3
mA/cm2 to 14.8 mA/cm2 and an efficiency of 2.13% was achieved. Also when In/S ratio was altered to 1.2/12, the
short circuit current density increased to 17.8 mA/cm2 with an improved fill factor of 32% and efficiency remaining
as 2%. Thus Cu/In and In/S ratios in the precursor solutions play a crucial role in determining the cell parameters

Holographic grating with good storage
life in poly(vinyl alcohol) based photopolymer film, prepared
by gravity settling method, with reduced concentration
of the dye was found to give good diffraction
efficiency without crosslinking. The material was found
to show good diffraction efficiency and sensitivity (75%
diffraction efficiency at exposure energy of 80 mJ/cm2).
The shelf life of the photopolymer solution could be
improved by storage at a temperature 4 C in refrigerator

The differaction efficiency,sensitivity and storage life of Methylene Blue sencitized poly (vinyl chloride) film was improved by the addition of an electron donor in the matrix. The
addition of pyridine enhanced the diffraction efficiency by two times and storage life of the
gratings was increased to 2-3 days.

A methylene-blue-sensitized polymer blend of polyvinyl alcohol and polyacrylic acid is fabricated and
tested for holographic recording. It was found to have good characteristics such as high sensitivity,
storage stability, ease of fabrication, and environmental stability. Optimization of the ratio of polyvinyl
alcohol polyacrylic acid, the sensitizer concentration, pH, energy, diffraction efficiency measurements,
etc., have been done. pH is found to have a great influence on the recovery of the dye in this matrix.
The results of experimental investigations into the properties of this new material are reported.

An investigation on the panchromaticity of a silver-doped poly(vinyl alcohol)/acrylamide photopolymer
system is presented in this paper. Frequency-doubled Nd:YAG (532 nm) and Arþ (488 nm) lasers were
used for the characterization of the films. Previous studies using an He–Ne laser (632:8 nm) showed that
plane-wave transmission grating with a high diffraction efficiency of 75% could be stored in the optimized
film. From the present study, it was noted that transmission gratings with 70% diffraction efficiency
could be recorded using Arþ and Nd:YAG lasers, thereby elucidating the possibility of using the developed
photopolymer system as a competent panchromatic recording medium

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Polymer materials find application in optical storage technology,
namely in the development of high information density and fast access type
memories. A new polymer blend of methylene blue sensitized polyvinyl alcohol
(PVA) and polyacrylic acid (PAA) in methanol is prepared and characterized
and its comparison with methylene blue sensitized PVA in methanol and
complexed methylene blue sensitized polyvinyl chloride (CMBPVC) is presented.
The optical absorption spectra of the thin films of these polymers
showed a strong and broad absorption region at 670-650 nm, matching the
wavelength of the laser used. A very slow recovery of the dye on irradiation was
observed when a 7:3 blend of polyvinyl alcohol/polyacrylic acid at a pHof 3.8
and a sensitizer concentration of 4.67 10 5 g/ml were used. A diffraction
efficiency of up to 20% was observed for the MBPVA/alcohol system and an
energetic sensitivity of 2000 mJ/cm2 was obtained in the photosensitive films
with a spatial frequency of 588 lines/mm.

Photothermal deflection technique (PTD) is a non-destructive tool for measuring the temperature distribution
in and around a sample, due to various non-radiative decay processes occurring within the material. This tool
was used to measure the carrier transport properties of CuInS2 and CuInSe2 thin films. Films with thickness
<1 μm were prepared with different Cu/In ratios to vary the electrical properties. The surface recombination
velocity was least for Cu-rich films (5×105 cm/s for CuInS2, 1×103 cm/s for CuInSe2), while stoichiometric
films exhibited high mobility (0.6 cm2/V s for CuInS2, 32 cm2/V s for CuInSe2) and high minority carrier lifetime
(0.35 μs for CuInS2, 12 μs for CuInSe2

Effect of varying spray rate on the structure and optoelectronic properties of spray pyrolysed ZnO film
is analysed. ZnO films were characterised using different techniques such as X-ray diffraction (XRD),
photoluminescence, electrical resistivity measurement, and optical absorption. The XRD analysis proved
that, with the increase in spray rate, orientation of the grains changed from (1 0 1) plane to (0 0 2) plane.
The films exhibited luminescence in two regions—one was the ‘near band-edge’ (NBE) (∼380 nm) emission
and the other one was the ‘blue-green emission’ (∼503 nm). Intensity of the blue-green emission
decreased after orientation of grains shifted to (0 0 2) plane. Scanning electron microscope (SEM) analysis
of the films asserts that spray rate has major role in improving the crystallographic properties of
the films. Moreover resistivity of the films could be lowered to 2.4×10−2 cm without any doping or
post-deposition annealing

SnS thin films were prepared using automated chemical spray pyrolysis (CSP) technique. Single-phase, p-type,
stoichiometric, SnS films with direct band gap of 1.33 eV and having very high absorption coefficient (N105/cm)
were deposited at substrate temperature of 375 °C. The role of substrate temperature in determining the
optoelectronic and structural properties of SnS films was established and concentration ratios of anionic and
cationic precursor solutions were optimized. n-type SnS samples were also prepared using CSP technique at the
same substrate temperature of 375 °C, which facilitates sequential deposition of SnS homojunction. A
comprehensive analysis of both types of films was done using x-ray diffraction, energy dispersive x-ray analysis,
scanning electron microscopy, atomic force microscopy, optical absorption and electrical measurements.
Deposition temperatures required for growth of other binary sulfide phases of tin such as SnS2, Sn2S3 were also
determined

Significant results of our experimental investigations on the dependence of pH on real time
transmission characteristics on recording media fabricated by doping PVC with complexed methylene blue
are presented. The optimum pH value for faster bleaching was found to be 4×5. In typical applications, the
illumination from one side, normal to the surface of this material, initiates a chemical sequence that records
the incident light pattern in the polymer. Thus direct imaging can be successfully done on this sample. The
recorded letters were very legible with good contrast and no scattering centres. Diffraction efficiency
measurements were also carried out on this material.

Poly(methyl)methacrylate was made photoconducting by molecular doping and the
photoconductivity was investigated using modulated photocurrent technique . Low-temperature
current-voltage measurements showed that the transport mechanism was thermally activated
hopping. An experimental investigation of the photoconductivity action spectrum along with
theoretical calculation enabled an estimation of the diffusion coefficient of the material. The
presence of states with a distribution of lifetimes could be understood from the frequency response
of the photocurrent . The photocurrent was due to the field-assisted dissociation of these states.

This work projects photoluminescence (PL) as an alternative technique to estimate the order of resistivity of zinc oxide (ZnO) thin
films. ZnO thin films, deposited using chemical spray pyrolysis (CSP) by varying the deposition parameters like solvent, spray rate,
pH of precursor, and so forth, have been used for this study. Variation in the deposition conditions has tremendous impact on the
luminescence properties as well as resistivity. Two emissions could be recorded for all samples—the near band edge emission (NBE)
at 380 nm and the deep level emission (DLE) at ∼500 nm which are competing in nature. It is observed that the ratio of intensities
of DLE to NBE (𝐼DLE/𝐼NBE) can be reduced by controlling oxygen incorporation in the sample. 𝐼-𝑉 measurements indicate that
restricting oxygen incorporation reduces resistivity considerably. Variation of 𝐼DLE/𝐼NBE and resistivity for samples prepared under
different deposition conditions is similar in nature. 𝐼DLE/𝐼NBE was always less than resistivity by an order for all samples.Thus from
PL measurements alone, the order of resistivity of the samples can be estimated.

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A new photopolymerizable recording media is introduced based on poly
(vinyl alcohol) and vinyl acetate sensitized with methylene blue. It is observed
that this MBPVA/VAc system can be reused a number of times without
significant decrease in diffraction efficiency. The PVA-VAc ratio was optimized
at 2:1. Diffraction efcienc4y of 6.3% was obtained without any fixing at a dye
concentration of 9.3 x 10- mol/l at an exposure of 750mJ/cm2. The material is
attractive on account of its reusability.

Files in this item: 1

A new photopolymerizable recording media is introduced based on poly
(vinyl alcohol) and vinyl acetate sensitized with methylene blue. It is observed
that this MBPVA/VAc system can be reused a number of times without
significant decrease in diffraction efficiency. The PVA-VAc ratio was optimized
at 2:1. Diffraction efficiency of 6.3% was obtained without any fixing at a dye
concentration of 9.3 10 4 mol/l at an exposure of 750 mJ/cm2. The material is
attractive on account of its reusability.

Effect of chlorine doping on the opto-electronic properties of β-In2S3 thin film, deposited by spray pyrolysis
technique is studied for the first time. Chlorine was incorporated in the spray solution, using HCl. Pristine
sample prepared using In(NO3)3 and thiourea as the precursors showed very low photosensitivity. But upon
adding optimum quantity of chlorine, the photosensitivity increased by 3 orders. X-ray analysis revealed that
crystallinity was also increasing up to this optimum level of Cl concentration. It was also observed that
samples with high photosensitivity were having higher band gap. The present study proved that doping with
chlorine was beneficial as this could result in forming crystalline and photosensitive films of indium sulfide.

Incorporation of silver ions into a dye-sensitized poly(vinyl alcohol)/acrylamide photopolymer is observed
to give better performance compared to other metal-ion-doped photopolymer holographic recording
media. Plane-wave transmission gratings were recorded in the photopolymer films using a He–Ne
laser, and various holographic parameters were optimized so as to explore maximum potential of the
material for various holographic applications. Silver-doped films showed good energy sensitivity,
and gratings recorded in optimized film exhibited a diffraction efficiency of more than 75%. The
potential of the material for holographic data storage applications is also studied using peristrophic
multiplexing

In this paper, we report the results of investigations on the
potential of spray pyrolysis technique in depositing electron
selective layer over larger area for the fabrication of inverted
bulk-heterojunction polymer solar cells. The electron selective
layer (In2S3) was deposited using spray pyrolysis technique and
the linear heterojunction device thus fabricated exhibited good
uniformity in photovoltaic properties throughout the area of the
device. An MEH-PPV:PCBM inverted bulk-heterojunction
device with In2S3 electron selective layer (active area of
3.25 3.25 cm2) was also fabricated and tested under indoor
and outdoor conditions. Fromthe indoor measurements employing
a tungsten halogen lamp (50mW/cm2 illumination), an opencircuit
voltage of 0.41V and a short-circuit current of 5.6mA
were obtained. On the other hand, the outdoor measurements
under direct sunlight (74mW/cm2) yielded an open-circuit
voltage of 0.46V and a short-circuit current of 9.37mA